System and method for detecting heart failure and pulmonary edema based on ventricular end-diastolic pressure using an implantable medical device

Abstract

Techniques are provided for detecting left ventricular end diastolic pressure (LV EDP) using a pressure sensor implanted within the heart of a patient and for detecting and evaluating heart failure and pulmonary edema based on LV EDP. Briefly, the peak of the R-wave of an intracardiac electrogram (IEGM) is used to trigger the measurement of a pressure value within the left ventricle. This pressure value is deemed to be representative of LV EDP. In this manner, LV EDP is easily detected merely by measuring pressure at one point within the heartbeat-thereby eliminating any need to track ventricular pressure throughout the heartbeat. Techniques for detecting and evaluating heart failure and pulmonary edema based on the R-wave triggered LV EDP measurements are also set forth herein.

What is claimed is: 
     
       1. A method for detecting ventricular end diastolic pressure (EDP) within a patient having an implantable medical device equipped with at least one electrical cardiac sensing lead and a pressure sensor, the method comprising:
 detecting a peak amplitude within an electrical cardiac signal sensed during a heartbeat using the lead; 
 detecting a value representative of ventricular EDP for the heartbeat using the pressure sensor by triggering the measurement of left ventricular pressure in response to the detection of the peak amplitude within the electrical cardiac signal; 
 tracking respiration cycles; 
 tracking heart beats; 
 averaging ventricular EDP over heart beats during one respiration cycle; 
 identifying changes in averaged ventricular EDP due to respiration; and 
 detecting changes, if any, in averaged ventricular EDP not due to respiration. 
 
     
     
       2. The method of  claim 1  wherein the peak amplitude detected during the heartbeat is the peak of an R-wave portion of a ORS-complex of the heartbeat. 
     
     
       3. The method of  claim 1  wherein the pressure is measured at a time within a detection window surrounding the peak of the electrical cardiac signal, the window extending throughout the end diastolic phase of the heartbeat. 
     
     
       4. The method of  claim 1  further comprising tracking changes in ventricular EDP over time. 
     
     
       5. The method of  claim 4  wherein tracking changes in ventricular EDP over time comprises tracking ventricular EDP over a plurality of heartbeats. 
     
     
       6. The method of  claim 4  further comprising detecting the onset of a selected medical condition within the patient based on changes in ventricular EDP overtime. 
     
     
       7. The method of  claim 6  wherein the medical condition is any condition associated with a detectable change in ventricular EDP over time. 
     
     
       8. The method of  claim 6  wherein detecting the onset of a selected medical condition is performed by determining whether an increase in LV EDP exceeds a heart failure detection threshold. 
     
     
       9. The method of  claim 6  wherein detecting the onset of a selected medical condition is performed by determining whether an increase in LV EDP exceeds a pulmonary edema detection threshold. 
     
     
       10. The method of  claim 6  further comprising delivering therapy in response to the medical condition. 
     
     
       11. The method of  claim 10  wherein delivering therapy comprises delivering cardiac resynchronization therapy (CRT). 
     
     
       12. The method of  claim 10  wherein the device is equipped with an implantable drug pump and wherein delivering therapy comprises delivering selected medications to the patient using the drug pump. 
     
     
       13. The method of  claim 6  further comprising generating a warning signal in response to the medical condition. 
     
     
       14. The method of  claim 6  wherein detecting the onset of the medical condition is performed by an external programmer device based on signals received from the implanted device. 
     
     
       15. The method of  claim 6  further comprising evaluating the severity of the medical condition based on the values representative of LV EDP. 
     
     
       16. The method of  claim 15  further comprising tracking changes, if any, in the severity of the medical condition within the patient based on any changes over time in the values representative of LV EDP. 
     
     
       17. A method for detecting the onset of a medical condition within a patient having an implantable medical device equipped with at least one electrical cardiac sensing lead and a pressure sensor, the method comprising:
 detecting peak amplitudes within electrical cardiac signals sensed during each of a plurality of heartbeats using the lead; 
 detecting a value representative of ventricular end diastolic pressure (EDP) for each of the heartbeats using the pressure sensor by triggering a measurement of left ventricular pressure in response to the detection of the peak amplitude of the electrical cardiac signal within the heartbeat; 
 detecting the onset of selected medical conditions within the patient based on changes in ventricular EDP over time; 
 averaging ventricular EDP over heart beats during one respiration cycle; 
 identifying changes in averaged ventricular EDP due to respiration; and 
 detecting changes, if any, in averaged ventricular EDP not due to respiration. 
 
     
     
       18. A system for detecting ventricular end diastolic pressure (EDP) within a patient having an implantable medical device equipped with at least one electrical cardiac sensing lead and a pressure sensor, the system comprising:
 an R-wave detection unit operative to detect a peak amplitude within an electrical cardiac signal sensed during a heartbeat using the lead; 
 an R-wave-triggered detection unit operative to detect a value representative of ventricular EDP for the heartbeat using the pressure sensor by triggering a measurement of left ventricular pressure in response to the detection of the peak amplitude of the electrical cardiac signal 
 means for averaging ventricular EDP over heart beats during one respiration cycle; 
 means for identifying changes in averaged ventricular EDP due to respiration; and 
 means for detecting changes, if any, in averaged ventricular EDP not due to respiration. 
 
     
     
       19. A system for detecting ventricular end diastolic pressure (EDP) within a patient having an implantable medical device equipped with at least one electrical cardiac sensing lead and a pressure sensor, the system comprising:
 means for detecting a peak amplitude within an electrical cardiac signal sensed during a heartbeat using the leads; 
 means for detecting a value representative of ventricular EDP for the heartbeat using the pressure sensor by triggering a measurement of measuring left ventricular pressure in response to the detection of the peak amplitude of the electrical cardiac signal; 
 means for averaging ventricular EDP over heart beats during one respiration cycle; 
 means for identifying changes in averaged ventricular EDP due to respiration; and 
 means for detecting changes, if any, in averaged ventricular EDP not due to respiration.